1. Field of the Invention
This invention relates to a light-receiving module, in which an optical signal is converted into an electrical signal.
2. Related Prior Art
As shown in FIG. 9 and FIG. 10, a conventional light-receiving module has a semiconductor light-receiving device 102, such as a photodiode, a base 103 for mounting the light-receiving device 102, and a plurality of lead terminals 104 to 108. The semiconductor light-receiving device converts an incident optical signal to a corresponding electrical signal. The base 102 also mounts a semiconductor electronic device that amplifies the converted electrical signal and outputs the signal to an outside of the module through the lead terminal. A sealing material 109, such as a glass sealant, supports the lead terminals 104 to 108 that are not connecting to the base 103. The sealing material electrically isolates the lead terminals 104 to 108 from the base 102. In the conventional module, the base made of metal forms a hollow 110 in its backside opposing to the surface where the semiconductor device is mounted thereon. The sealing material is entirely filled up within the hollow.
The current optical communication requires a transmission speed over 10 Gbps. In such high-speed application, the conventional optical module shown in FIGS. 9 and 10 can not be applicable because a lead terminal through which an electrical signal is transmitted has not an impedance-matched configuration. When the electrical signal transmits such lead terminal, a reflection and a loss of the signal may occur at an impedance-mismatched portion. The higher the transmission speeds, the more serious this impedance-mismatched problem. Moreover, the higher the transmission speeds, the more the power consumption of the semiconductor device. In the conventional module, since the backside of the base is entirely filled up with the sealant that has less thermal conductivity than metal, the heat dissipation through the base is restricted.